Help with oil level sensor. **solved**

[Derek MacKinnon]

Still having issues with this oil level sensor. Good part of 6 months ive not touched the car.

Long story short. Car sat for maybe 1-1.5 years in my garage just going out for a mot. Did 50 miles in the last two years.

I’ve had this issue with the oil level sensor not reading oil level for some time now and have been trying to get to the bottom of it.

Basically I can’t reset the oil with the BC button when it’s fully warmed up or after driving a good amount of miles.

I don’t have the clock that spins when you reset it. I only have the -.- as you can see in the last photo.

I’ve got an autel now and had the codes read.
This comes up with oil condition sensor electrical fault.

A few months ago I pulled the plug off the sensor and made sure there were no breaks in the wiring. This was a nightmare as I couldn’t find where the other ends plugged into.

I ended up just last week buying a used engine wiring harness and found the wires for the sensor and had continuity between the sensor pins and the ends of the wires so no issues. I removed my harness off the car and couldn’t get continuity on one of the pins so thought there must be a break in the wiring somewhere. I did try and trace it on the old harness when I removed it but couldn’t trace it.

Anyway new harness in and that didn’t resolve the issue.

I have had a new genuine oil level sensor fitted so don’t know if this is faulty or if it’s related to the alternator code I’m also getting.

I also tried to reset the oil service through the odometer the same way you can reset brake pads and disks. This works fine for the disks and pads but it will not reset on the oil section. It stays at 140 miles no matter what I try.

I’m pulling my hair out. I guess I can take it to BMW but that’s a ferry trip and a 50 mile drive without oil level showing.

Anyone got any ideas on this issue or the alternator issue I seem to have too?

Thanks

[yardbro]

There has to be an issue with your wiring in this case, specifically with whatever portion directly goes to this connector. Testing for continuity is not enough, especially with the circuit entirely unloaded as is the case with the wiring harness just sitting on a desk or something. The DME having an internal fault here is possible, but very unlikely.

Try to pull the plug off again and check the 3 different pins individually, especially the Orange and Brown wires. You should have battery voltage on orange at all times, and a solid ground on brown. If you are able and know how, try to load this circuit with at least 2A to be sure that you're not getting a crazy voltage drop off or something. In this circuit fuse 16 is shared with many other components including the cam sensors so it's probably not going to be the fuse lol.

[Helmsman]

...last resort drain the oil and refill to ensure the engine has what it needs, and take it to the shop.

[Derek MacKinnon]

Originally Posted by yardbro

There has to be an issue with your wiring in this case, specifically with whatever portion directly goes to this connector. Testing for continuity is not enough, especially with the circuit entirely unloaded as is the case with the wiring harness just sitting on a desk or something. The DME having an internal fault here is possible, but very unlikely.

Try to pull the plug off again and check the 3 different pins individually, especially the Orange and Brown wires. You should have battery voltage on orange at all times, and a solid ground on brown. If you are able and know how, try to load this circuit with at least 2A to be sure that you're not getting a crazy voltage drop off or something. In this circuit fuse 16 is shared with many other components including the cam sensors so it's probably not going to be the fuse lol.

Thanks for this, ill get the pins checked when i get back from work in a week.

[Derek MacKinnon]

Originally Posted by Helmsman

...last resort drain the oil and refill to ensure the engine has what it needs, and take it to the shop.

Yep, its looking like this will be the case, I do have the option of a trailer but its an expense for the travel but it certainly gives me options, thanks.

[Helmsman]

Originally Posted by Derek MacKinnon

Yep, its looking like this will be the case, I do have the option of a trailer but its an expense for the travel but it certainly gives me options, thanks.

Of course. Did the same and ordered a trailer when I noticed my vanos cap was turned. Small money in the big scale of things...

[Derek MacKinnon]

Just to say I’ve finally gotten to the bottom of this issue.

Unplugged the alternator and ran the car up to temp.

The dash came back to life and my oil level was back to actually reading again. So it looks like the voltage regulator will need changed out on that alternator.

[RocketyMan]

That's a great diagnosis. The alternator also has a BSD/LIN signal going to it that most likely crashed the LIN going to the oil sensor. Good thinking!

[Derek MacKinnon]

Yeah it was a bit of a pain but glad its solved and hope it can help anyone else in the future.

Photos also rotated now.

Big thanks to yardbro for his help with the wiring and my questions.

[nowayout]

Related question regarding the oil level reading. How long or how many miles does it usually take to show the level reading on the dash?

[yardbro]

Originally Posted by nowayout

Related question regarding the oil level reading. How long or how many miles does it usually take to show the level reading on the dash?

Are you asking in general or in this specific case?

[nowayout]

Originally Posted by yardbro

Are you asking in general or in this specific case?

In general. As mine sometimes doesn't register if I am making trips under 15 min

[yardbro]

Originally Posted by nowayout

In general. As mine sometimes doesn't register if I am making trips under 15 min

Yeah that’s normal. The oil has to reach a certain temp before it will attempt to take a measurement. Sometimes you will find that if you come to a complete stop for a few minutes after driving a short while that it will give you the measurement whereas if you had kept driving it would take a bit longer.

[Derek MacKinnon]

I was about 10 minutes on idle on level ground before my level reading came back to life. I usually found it takes about that time from cold after an oil change too.

Here you can see my temp gauge seconds after my oil reading came back to life.

[Antz M3]

I’m experiencing exactly the same issues at the moment and I’ve completely ran out of ideas.
Had the same alternator code and oil level sensor code. Read up on it and thought my alternator might be going out (17yrs old so probs worth doing) - so replaced with refurbished Valeo one. Ran the car and both codes came straight back. Thought Ok must be the oil level sensor causing a problem - new sensor in and still the same two codes come up. Checked battery which is all fine and voltage is 14.15 with car running. Wiring looks fine as far as I can see. Completely stuck with this now

[ab987]

Originally Posted by Antz M3

I’m experiencing exactly the same issues at the moment and I’ve completely ran out of ideas.
Had the same alternator code and oil level sensor code. Read up on it and thought my alternator might be going out (17yrs old so probs worth doing) - so replaced with refurbished Valeo one. Ran the car and both codes came straight back. Thought Ok must be the oil level sensor causing a problem - new sensor in and still the same two codes come up. Checked battery which is all fine and voltage is 14.15 with car running. Wiring looks fine as far as I can see. Completely stuck with this now

Is the AC compressor or servotronic on BSD? If so try unplugging both of those and see if things spring back to life

[yardbro]

Originally Posted by ab987

Is the AC compressor or servotronic on BSD? If so try unplugging both of those and see if things spring back to life

Doesn't appear to be so. The diagrams only show a shared bus line between the oil level sensor and the alternator. I attached the diagram below.

Originally Posted by Antz M3

I’m experiencing exactly the same issues at the moment and I’ve completely ran out of ideas.
Had the same alternator code and oil level sensor code. Read up on it and thought my alternator might be going out (17yrs old so probs worth doing) - so replaced with refurbished Valeo one. Ran the car and both codes came straight back. Thought Ok must be the oil level sensor causing a problem - new sensor in and still the same two codes come up. Checked battery which is all fine and voltage is 14.15 with car running. Wiring looks fine as far as I can see. Completely stuck with this now

See if you can get access to a good scan tool or preferably ISTA and see if the sensor is providing any measurements at all. Even though the car doesn't show the oil level reading through the dash, there should be some provided measurement available within the diagnostic software that is used in the case there is something egregious going on with the oil level, like no oil at all. The car is smart enough to know if you are down 2 quarts on startup and things along those lines. If you have the same two codes as OP, im willing to bet there is something going on with that BSD line, it just doesn't happen to be within the alternator or the oil condition sensor itself obviously.

[RocketyMan]

Not sure if it was mentioned earlier, but the IBS is connected to the LIN as well. See the internal splice of all 3 linked together.

[Andreye90]

On the BSD, You will have water pump ,alternator , oil sensor and IBS.
If any of this is faulty you will get BSD error.
I have changed the water pump , oil sensor , alernator ans IBS ans still can’t read the oil or reset the oil.
My problem will probably be that my alternator only runs 13.4v and I think that’s a bit low.
I’m going to take out the alternator as well and semif this will sort out the problem.

[Erickuokwa]

Hi! I just am running into this issue. Code p1521 - replaced with oem oil level sensor, but now it does not read at all. Just shows -.- no spinning clock at all. I notice sometimes, when my car is warm, my temp drops to 0 and steering wheel reads a crazy 405degrees. I’m about to disconnect alternator and do the test. Any others can chime in to help?

[Erickuokwa]

Does this potentially mean the alternator? Should I also get a new battery while I’m here?

[Baekhyunn]

Originally Posted by Erickuokwa

Does this potentially mean the alternator? Should I also get a new battery while I’m here?

were you able to resolve this?